Insulator for electric or other wires



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CLINTON SPROAT AND EDWARD N. TARR, O F TAUNTON, MASSACHUSETTS.

INSULATOR FOR ELECTRIC OR OTHER WIRES.

SPECIFICATION forming part of Letters Patent No. 544,778, dated August20, 18 95. 7

Application filedJannary 2 1895. Serial No. 533,548- (No inodel.)

To whom it may concern:

Be it known that we, CLINTON SPROAT and EDWARD N. TARR, citizens of theUnited States, residing at Taunton, in the county of 'Bristol and Stateof Massachusetts, have in I novel construction and arrangement of partshereinafter described, whereby the use of ties is done away with and theinsulator rendered more perfect in construction. A The nature of theinvention in detail is fully described below, and illustrated in theaccompanying drawings, in which- Figure 1 is an elevation of ourimproved insulator applied to a pin and with wires laid in positiontherein. Fig. 2 is a central vertical section of the same. Fig. 3 is aplan view of the upper surface of the base. Fig. 4 is a plan view of theunder side of the head or cup.

Similar letters of reference indicate corresponding parts.

A represents the pin, made of any suitable material, whose upper portionA is screwthreaded.

B is the base, made of glass, porcelain, or other non-conductingmaterial, internally screw-threaded to correspond with the pin andformed on its under side into the ordinary petticoat B. The uppersurface of the base is provided with grooves 0, preferably madeV-shaped' in cross-section, two sets of two grooves each being usuallyprovided, as

.shown in Fig. 3, thus furnishing accommodation for one or more wires.Each of these grooves is furnished with, say, three transverse ribs orprojections G of reverse V shape, one such projection extending upwardfrom one side of a V-shaped groove from the upper edge to the bottomthereof, and two extending upward from the opposite side of the V-shaped groove and extending from the upper edge to the bottom thereof.

D is the head or cup internally screwthreaded to correspond with thethread on the pin A. The under surface of this head is formed into aseries of concentric annular corrugations E.

cured on the wire.

H represents a couple of wires covered with insulation, although ofcourse bare wires may be used.

J is a circularfiange or partition extending up from the base B, nextthe central opening therein, into an annular chamber K, formed on theunder side of the head D around the threaded opening for the receptionof the pin.

In operation, the wires H are laid in the V- shaped grooves C after thebase 13 has been screwed onto the pin by means of an ordinary spannerinserted in the opening 19. The head or cup D is then screwed on bymeans of a spanner in the openingd and crowded down hard upon the wiresH. The effect is to crowd the wires down into the grooves C,

causing the V-shaped projections O to embed themselves in the insulationon the under side of the Wires. The upper sides of the wires havecrowded down upon and into them the annular corrugations E. By thismeans the use of ties is absolutely unneccessary, as the grip, both ofthe projections C and the corrugations E, is very great. It will readilybe seen that by reason of the arrangement of the projections O onopposite sides of the grooves a greater surface of the under side of thewire is gripped, while as the said V-shaped projections are settransversely with the grooves a comparatively broad hold is se-Attention is called to the fact that the wires do not cross thecorrugations E radially, but describe geometrical chords. By this meanseach corrugation has a very much longer contact'than would be the caseif the intersection were radial, and hence the frictional hold is verygreat. The circular partition J prevents any possible electricalconnection between a wire which is uninsulated or from which theinsulation is worn .ofi and the pin, and hence prevents ground- 'base B,of the cup or head D provided with a series of annular concentriccorrugations E, and means whereby said head or cup may be pressed downupon a wire lying on said base, substantially as set forth.

2. In an insulator, the base B provided with I the straight grooves O,and the head or cup side with the grooves O, and the head or cup Dprovided with the concentric corrugations l) internally screw tlireadmand provided E, said straight grooves being adapted to rcwith theconcentric corrugations E on its ccive the Wires and extendin5., acrossthe connndcr side, substantially as described.

5 centric corrugations in. the line or direction of a chord,substantially described. CLINTON SPROAT.

Thellcreindescribedimprovedinsulator, EDWARD N. TARR. consistingessentially oi the externally screw- Witnesses: threaded pin A A, thebase 15 internally HENRY N. \VlLLIAMS, 1o screw-tlircadcd and providedon its upper E. A. \V0OD'J-1URY.

